The present invention relates to a motor/generator apparatus for a vehicle which can operate as a motor and a generator.
There is disclosed in JP-A-62-93435 a control system for an internal combustion engine having an AC machine which is also used as a starter motor which output is coupled to an output shaft of the engine. The AC machine is used as a motor or an alternator, whereby, at the time of starting a vehicle, an output driving force of the motor assists a smooth acceleration of the vehicle, while, at the time of decelerating or stopping the vehicle, a braking force is converted to electric power to store it in a battery.
This system includes a gear mechanism for engagement with a ring gear provided at an outer periphery of a flywheel of the internal combustion engine, a small gear provided coaxially with the output shaft of the AC machine for engagement with the gear mechanism, and an electromagnetic clutch for clamping the gear mechanism. In the engine start mode, the electromagnetic clutch is turned OFF so that the output shaft of the AC machine is coupled with the engine via the small gear and gear mechanism with a large reduction gear ratio, in which case the AC machine operates as a motor. When the engine is stopped, on the other hand, the electromagnetic clutch is turned ON so that the output shaft of the AC machine is coupled to the engine via the small gear and gear mechanism with a small reduction gear ratio, in which case the AC machine operates as a generator.
In the above prior art, when the engine starts, the rotary shaft of the AC machine is rotated in a direction opposite to the rotation direction of the small gear which forms a ring gear in planetary gears, it is considered, when the electromagnetic clutch is engaged, that the rotational speed of the engine abruptly decreases under the influence of a rotational inertia of the rotary shaft of the AC machine. Such a circumstance is not preferable from the viewpoint of purposes of improving the ride quality and stability of the vehicle.
It is therefore an object of the present invention to provide a motor/generator apparatus for a motor vehicle which can be driven in such a manner as to improve the riding comfort and stability of the vehicle.
In accordance with an aspect of the present invention, the above object is attained by a motor/generator apparatus for a vehicle which includes an electric machine acting as a motor or as a generator and also includes a transmission for bi-directionally transmitting a driving force between the electric machine and a crank shaft of an engine and which is arranged so that the direction of a rotary shaft of the transmission when the electric machine functions as the motor is the same as that when the electric machine functions as the generator.
Further, the motor/generator apparatus is arranged so that the rotational direction of a rotor when the electric machine operates as the motor is made the same as the rotational direction of an input/output shaft coupled to the crank shaft when the electric machine operates as the generator.